Evrim Yazgin
Cosmos science journalist
Catalysis is the process where a chemical reaction is sped up. For the first time, scientists have directly observed a catalytic reaction at the atomic scale in real time.
The reaction involves the removal of hydrogen atoms from alcohol molecules. In amazing new videos, individual atoms are seen moving and shaking during the reaction. The study is published in the journal Chem.
“By visualising this process and following the reaction mechanisms, we can understand exactly what’s happening in the finest detail,” says first author Yosi Kratish from Northwestern University in the US. “In the past, we haven’t been able to see how atoms move. Now we can.
“When I realised what we accomplished, I had to close my laptop and take a break for a few hours. Nobody has done this before in catalysis, so I was stunned.”
The observations were made using SMART-EM, single-molecule atomic-resolution time-resolved electron microscopy. The powerful device enables researchers to watch individual molecules react in real time.
“Most conventional transmission electron microscopy (TEM) techniques operate at conditions that easily damage organic molecules,” Kratish adds. “This makes it extremely challenging to directly observe sensitive catalysts or organic matter during a reaction using traditional TEM methods.”
The new SMART-EM technique allows for image capture of delicate organic molecules. It uses a far lower electron dose and energy.
About 85% of industrial catalysts are heterogenous, meaning they are solid materials that interact with liquids and gases. Such catalysts are stable and efficient.
“But there’s a major disadvantage,” Kratish says. “They have an unknown number of sites where reactions can occur. So, we don’t fully understand where and how reactions take place. That means we cannot exactly figure out what part of the catalyst is most effective.”
This makes it difficult if you want to watch a catalyst doing its thing.
So, the team designed a catalyst with a well-defined active site where the reaction would take place. It comprised molybdenum oxide particles anchored to a carbon nanotube in the shape of a cone.
“Having a single site is a lot more convenient,” Kratish says. “We can pick a good site to monitor and really zoom into it.”
“Catalysts make modern life possible,” says senior author Tobin J Marks, also at Northwestern. “They are used to make everything from fuel and fertilisers to plastics and medicines. To make chemical processes more efficient and environmentally friendly, we need to understand exactly how catalysts work at the atomic level. Our study is a big step toward achieving that.”
